“No kind of immigration restriction is unconstitutional,” said Jan C. Ting, professor at Temple University School of Law and a former commissioner for the Immigration and Naturalization Services. “The U.S. government can exclude a foreign national on any basis.”

He went on to explain that over 100 years of legal precedent show that the U.S. government can make whatever kind of immigration laws and restrictions on foreigners allowed in the country that it sees fit to make.

“The statutes are clear: immigration is different from all other aspects of the law,” Ting said. “The Supreme Court has ruled we can enact laws against foreign nationals that would not be permissible to apply to citizens. The courts historically have no role in these decisions.”

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He added that it would be unlikely for the court to overturn a policy similar to the one proposed by Trump, as that would be undoing years of precedent and extending civil and constitutional rights to foreign nationals.

Eric Posner, a professor at the University of Chicago School of Law and an oft-cited legal expert, agreed that Trump’s proposed moratorium would pass constitutional scrutiny by the courts.

Posner wrote in a recent blog post that “constitutional protections that normally benefit Americans and people on American territory do not apply when Congress decides who to admit and who to exclude as immigrants or other entrants,” so therefore Trump’s proposal would not be unconstitutional.

Furthermore, Posner also wrote that Trump could conceivably impose his moratorium on Muslim immigration without any action from Congress if he could prove that some Muslim immigrants pose a national security threat, something easily provable from a legal perspective.

Whatever other arguments might be made for or against Trump’s plan to halt Muslim immigration into the United States for a period of time in order for the government to sort out its immigration issues, it is in fact legal and constitutional.